Table 2.

GTPCH Overexpression Results in de Novo BH4 Synthesis in Murine Fibroblast Implantation

Condition	Total biopterin (pmol/mg)	BH4 (pmol/mg)
GCHtet-off	216.1 ± 35.9*	198.5 ± 32.5*
+ DOX	23.7 ± 3.2	12.2 ± 3.0
+ DAHP	93.4 ± 20.3	81.0 ± 19.1

GCHtet-off cells (1 × 10⁷) were injected and treated with either Dox or DAHP as for Figure 5. Tumor tissues were homogenized, and biopterin levels were determined by high-performance liquid chromatography using both acid-base oxidation with fluorometric detection. Values shown are the means ± SEM of animals 

^1-8851(*P < 0.05 vs. Dox or DAHP determined by ANOVA).